Solar Cell Degradation During the 26kW Electric Propulsion Space Experiment (ESEX) Flight
Abstract
The United States Air Force Research Laboratory's Electric Propulsion Space Experiment (ESEX) was launched and operated in early 1999 in order to demonstrate the compatibility and readiness of a 30-kW class ammonia arcjet for satellite propulsion applications. As part of this flight, an array of on-board contamination sensors was used to assess the effect of the arcjet and other environments on the spacecraft. The sensors consisted of microbalances to measure material deposition, radiometers to assess material degradation due to thermal radiation, and solar cell segments to investigate solar array degradation. During firings, the solar cell segments show decreasing open-circuit voltage probably attributable to an additional electrical load provided by a short through the plume plasma. Over eight firings of the ESEX arcjet, and 33 minutes, 26 seconds operating time, the solar cells also exhibit a 3% decrease in short-circuit current, attributable to decreased solar transmission of the cover glass. However, no effects associated with the arcjet are observed on the spacecraft solar arrays. In general, the contamination effects are observed only on the solar cells sensor segments placed very near the thruster exhaust nozzle. In the backplane of the thruster, where the main arrays are located, no deleterious effects are observed, indicating that while engineering measures may be required for equipment in the immediate vicinity of the thruster, the arcjet environment is generally benign.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 11, 2001
- Accession Number
- ADA404891
Entities
People
- D. R. Bromaghim
- G. G. Spanjers
- J. H. Schilling
Organizations
- Air Force Research Laboratory